Extra-intestinal manifestations in patients with MYH-associated polyposis (MAP)

MYH-associated polyposis (MAP) is an autosomal recessive variant of FAP, which
carries a high risk of colorectal cancer (CRC) development. Besides gene
testing and endoscopy, the finding of extra-intestinal manifestations can serve
as a diagnostic tool to identify FAP patients with an unknown APC mutation. In
MAP, extra-intestinal manifestations have been reported (CHRPE, osteomas,
dermal lesions and odontomas). However, these reports have all been
retrospective and therefore unreliable. By prospectively assessing the
prevalence of these lesions in patients with MAP, the finding of
extra-intestinal manifestations could prove to be useful in detecting unknown
asymptomatic MAP patients.

The aim of this study is to prospectively assess the occurrence of
extra-intestinal manifestations in patients with MAP.

All included MYH patients will be interviewed focussing on past medical
history, dental abnormalities, orthodontic history and skin lesions. A physical
examination will be performed for detection of dermal lesions. Furthermore,
patients will undergo an oral & maxillofacial examination and an OPG of the jaw
will be made. Patients undergoing tooth extraction will serve as a control
group. Finally, an ophthalmic examination, for the detection of CHRPE, will be
performed. Consecutive patients attending the outpatient clinic Ophthalmology
will serve as a control group.

In this study each patient will receive an OPG of the jaw. This carries an
effective radiation dose of approximately 0.1 mSv which is less than the yearly
background level of natural radiation of 2-2.5 mSv in the Netherlands.